GB1604047A - Decoration of ceramic articles - Google Patents

Description

(54) DECORATION OF CERAMIC ARTICLES (71) We, JAMES BROADHURST & SONS LIMITED, a British Company, of Portland Pottery, Fenton, Stoke-on-Trent, Staffordshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to the decoration of ceramic articles.

Attractive decorative effects can be obtained on ceramic articles such as ceramic tableware by application of a pattern having raised areas of solid colour producing an embossed effect. Hitherto this effect has been produced by hand painting the coloured areas with a relatively thick layer of colouring medium, but this suffers from the disadvantage that it is a skilled and time consuming operation and depends for consistent results on the proficiency of the decorating operative.

It is an object of the present invention to provide a means for producing decoarative effects of this kind without requiring separate hand painting of the articles.

According to the invention there is provided a method of producing a raised decorative effect on a ceramic article comprising applying to the article a substantially linework pattern formed of a glaze-displacing colouring medium (as herein defined) and solid colour formed of a non-reactive colouring medium within areas defined by lines of the pattern, applying and retaining a coating of a glaze medium over the decorated area and subjecting the article to a firing operation wherein glaze is displaced from the linework pattern and on to the solid colour areas which are so dimensioned that the glaze displaced thereon produces a raised or embossed effect.

The term "glaze displacing colouring medium" is used herein to refer to a colouring medium having the property of displacing an overlying glaze medium during subsequent firing but does not include so-called glaze repellent mediums which have the effect of repelling glaze before firing thereby leaving areas of the article effectively unglazed. Glaze-dispIacing colouring mediums as referred to herein produce an article in which the entire surface is coated with glaze but the coating is thinner at those areas decorated with the glaze displacing medium than at other areas of the surface. The term non-reactive colouring medium is intended to cover all colouring mediums other than glaze-displacing and glaze-repellent mediums.

The linework or outline pattern and the areas of solid colour are preferably applied to the articles in the so called 'biscuit state by direct screen printing Mternatively they may be applied to a separate lithograph or transfer which is then ed to the surface of the article.

Either the outline pattern or the areas of solid colour may be applied to the article first. Preferably the colouring medium first applied is a thermoplastic colouring medium which dries upon contact with the surface of the article and enables the second colouring medium to be applied immediately thereafter.

Where the decoration is applied direct to the surface of the article only a single firing operation is necessary after application of the glaze coating to produce the finished decorated article. Where a transfer ar lithograph is utilized a preliminary "hardening on" fire will generally be necessary to adhere the pattern to the surface of the article and remove the protective cover coat from the transfer. The article is then glazed and subjected to a further firing in the same manner as the directly decorated article.

It is also possible to apply the pattern to the article in the unfired clay state by printing or by means of a transfer or the like.

In one arrangement described by way of example, a first pattern consisting of spaced areas of solid colour is applied to the rim of a plate in the 'biscuit' state by direct screen printing using a thermoplastic colouring medium. The colour dries immediately upon contact with the surface of the plate and a second pattern in outline form is then screen printed over the first pattern, the arrangement being such that the two patterns are in register and the areas of solid colour are embraced within regions of the outline pattern. The outline pattern is in a glazedisplacing colouring medium as herein defined so that it partly repels an overlying glaze coating during subsequent firing.Suitable glaze on placing colouring mediums are obtainable from Harrison Mayer Limited, of Meir, Stoke-on-Trent and include their Colour Numbers 28172547 (reactive brown), 28152328 (reactive green and 28161637 (reactive pink). Other colouring mediums having similar properties may be utilized and these may be dispersed in different carrier mediums dependent on the method of application. In the exemplary embodiment the medium is one suitable for screen printing purposes.

After application of the two patterns in sequence, the article is provided with a transparent glaze coating on one or both surfaces. This may be applied by any conventional technique such as dipping, spraying or the like. The decorated and glazed article is then subjected to a firing operation at a temperature of the order of 1040 to 10600C.

This causes partial displacement of the glaze medium from the outline pattern due to the nature of the colouring medium in which that pattern is applied, and since the areas of solid colour are surrounded by portions of the outline pattern the glaze medium collects and merges over the solid coloured areas producing an embossed effect in the finished article.

By virtue of the process described an attractive decorative effect having raised areas of solid colour within an outline pattern is obtained. The effect is similar to that which can be obtained by hand painting of the raised areas but it is not dependent on operative skill and can be carried out rapidly and with high repetition accuracy on a mass production basis.

In an alternative technique the patterns are applied to a transfer at lithograph by screen printing in the manner described above in relation to the direct decoration of the article. The transfer is provided with the usual protective cover coat and is then applied to the surface of the article to be decorated in the conventional manner. After application the article is subjected to a preliminary 'hardening-on' fire which serves to adhere the pattern to the surface of the article and burn off the protective cover coat.

This firing is generally carried out at a temperature of the order of 740 to 7600C.

The article is then provided with a glaze coating by any conventional means and is subjected to a further firing at a temperature in the order of 1040 to 10600C during which the glaze is repelled from the outline pattern on to the areas of solid colour thereby producing the embossed effect previously referred to.

Various modifications may be made without departing from the invention. For example two or more outline patterns of solid colour areas or two or more outline patterns may be provided. In this case it is preferred that the patterns first applied are in a thereon plastic colouring medium in order that the various patterns may be applied immediately one after the other. This enables the full decoration to be applied rapidly and also facilitates maintenances of correct registration between the various patterns. If desired a coloured or tinted glaze medium may be utilized.

It is also possible to apply the decorative patterns direct to the surface of an article in the unfired clay state by screen printing or other conventional techniques. In this case a higher firing temperature is required in order to produce the finished article and this can result in a change in colour of the decorating medium. This is however acceptable provided that the final colour is aesthetically satisfactory. A suitable firing temperature is of the order of 1140 to 1 1700C.

It should be appreciated that while reference has been made to the use of glaze displacing and non-reactive colouring mediums in applying the decoration, this does not preclude the possibility that some areas of the article either within or outside the area decorated by the method of the present invention could be decorated using glazerepellent colouring mediums.

WHAT WE CLAIM IS: 1. A method of producing a raised decorative effect on a ceramic article, comprising applying to the article a substantially limework pattern formed of a glaze-displacing colouring medium (as herein defined) and solid colour formed of a non-reactive colouring medium within areas defined by lines of the patter, applying and retaining a coating of a glaze medium over the decorated area and subjecting the article to a firing operation wherein glaze is displaced from the limework pattern and on to the solid colour areas which are so dimensioned that the glaze displaced thereon produces a raised or embossed effect.

2. A method according to claim 1 wherein the outline pattern and the areas of solid colour are applied sequentially to the article, whichever is applied first being in a thermoplastic colouring medium.

3. A method according to claim 1 or 2 wherein the linework pattern and the solid colour areas are applied directly on to the surface of the article by screen printing.

4. A method according to claim 3 wherein said firing operation comprises

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. arrangement being such that the two patterns are in register and the areas of solid colour are embraced within regions of the outline pattern. The outline pattern is in a glazedisplacing colouring medium as herein defined so that it partly repels an overlying glaze coating during subsequent firing. Suitable glaze on placing colouring mediums are obtainable from Harrison Mayer Limited, of Meir, Stoke-on-Trent and include their Colour Numbers 28172547 (reactive brown), 28152328 (reactive green and 28161637 (reactive pink). Other colouring mediums having similar properties may be utilized and these may be dispersed in different carrier mediums dependent on the method of application. In the exemplary embodiment the medium is one suitable for screen printing purposes. After application of the two patterns in sequence, the article is provided with a transparent glaze coating on one or both surfaces. This may be applied by any conventional technique such as dipping, spraying or the like. The decorated and glazed article is then subjected to a firing operation at a temperature of the order of 1040 to 10600C. This causes partial displacement of the glaze medium from the outline pattern due to the nature of the colouring medium in which that pattern is applied, and since the areas of solid colour are surrounded by portions of the outline pattern the glaze medium collects and merges over the solid coloured areas producing an embossed effect in the finished article. By virtue of the process described an attractive decorative effect having raised areas of solid colour within an outline pattern is obtained. The effect is similar to that which can be obtained by hand painting of the raised areas but it is not dependent on operative skill and can be carried out rapidly and with high repetition accuracy on a mass production basis. In an alternative technique the patterns are applied to a transfer at lithograph by screen printing in the manner described above in relation to the direct decoration of the article. The transfer is provided with the usual protective cover coat and is then applied to the surface of the article to be decorated in the conventional manner. After application the article is subjected to a preliminary 'hardening-on' fire which serves to adhere the pattern to the surface of the article and burn off the protective cover coat. This firing is generally carried out at a temperature of the order of 740 to 7600C. The article is then provided with a glaze coating by any conventional means and is subjected to a further firing at a temperature in the order of 1040 to 10600C during which the glaze is repelled from the outline pattern on to the areas of solid colour thereby producing the embossed effect previously referred to. Various modifications may be made without departing from the invention. For example two or more outline patterns of solid colour areas or two or more outline patterns may be provided. In this case it is preferred that the patterns first applied are in a thereon plastic colouring medium in order that the various patterns may be applied immediately one after the other. This enables the full decoration to be applied rapidly and also facilitates maintenances of correct registration between the various patterns. If desired a coloured or tinted glaze medium may be utilized. It is also possible to apply the decorative patterns direct to the surface of an article in the unfired clay state by screen printing or other conventional techniques. In this case a higher firing temperature is required in order to produce the finished article and this can result in a change in colour of the decorating medium. This is however acceptable provided that the final colour is aesthetically satisfactory. A suitable firing temperature is of the order of 1140 to 1 1700C. It should be appreciated that while reference has been made to the use of glaze displacing and non-reactive colouring mediums in applying the decoration, this does not preclude the possibility that some areas of the article either within or outside the area decorated by the method of the present invention could be decorated using glazerepellent colouring mediums. WHAT WE CLAIM IS:

1. A method of producing a raised decorative effect on a ceramic article, comprising applying to the article a substantially limework pattern formed of a glaze-displacing colouring medium (as herein defined) and solid colour formed of a non-reactive colouring medium within areas defined by lines of the patter, applying and retaining a coating of a glaze medium over the decorated area and subjecting the article to a firing operation wherein glaze is displaced from the limework pattern and on to the solid colour areas which are so dimensioned that the glaze displaced thereon produces a raised or embossed effect.

2. A method according to claim 1 wherein the outline pattern and the areas of solid colour are applied sequentially to the article, whichever is applied first being in a thermoplastic colouring medium.

3. A method according to claim 1 or 2 wherein the linework pattern and the solid colour areas are applied directly on to the surface of the article by screen printing.

4. A method according to claim 3 wherein said firing operation comprises

a single firing at a temperature of the order of 1040 to 10600C.

5. A method according to claim 1 or 2 wherein the linework pattern and the solid colour areas are applied to a lithograph or transfer which is then affixed to the surface of the article.

6. A method according to claim 5 wherein said firing operation comprises a first firing at a relatively low temperature to adhere the pattern to the surface of the article and a second firing at a relatively high temperature, said glaze medium being applied to the decorated area between said first and second firings.

7. A method according to any preceding claim wherein two or more limework patterns are applied to the article.

8. A method according to any preceding claim wherein two or more patterns of solid colour areas are applied to the article.

9. A method according to any preceding claim wherein said glaze medium is tinted or coloured.

10. A method of producing a raised decorative effect on a ceramic article substantially as hereinbefore described.

11. A ceramic article decorated by the method according to any preceding claim.

12. A decorated ceramic article substantially as hereinbefore described.